我正在尝试将输入字段中的值插入到数组中然后将其存储在localstorage中,但问题是每次插入新值时它都会替换旧值,而我希望将其添加到现有值中。如果这是一个愚蠢的问题,请耐心等待,我是新手:)
<html>
<body>
<form>
<input id="textInput" type=text>
<input type=button onclick="myFunction()" value="Add Number"/>
</form>
<div id="output"><div>
<script>
function myFunction() {
var sports = ["soccer", "baseball"];
var newSport = document.getElementById('textInput').value;
sports.push(newSport)
window.localStorage.setItem("sportskey", sports);
document.getElementById('output').innerHTML = window.localStorage.getItem('sportskey');
}
</script>
</body>
</html>
答案 0 :(得分:1)
您的sports
变量是函数的本地变量,因此每次函数运行时它都会重新初始化。要修复它,请将声明移到函数外部。
另外,正如@RocketHazmat指出的那样,你只能存储一个字符串。因此,您的新代码段应如下所示:
var sports = ["soccer", "baseball"]; //global scope
function myFunction() {
var newSport = document.getElementById('textInput').value;
sports.push(newSport)
window.localStorage.setItem("sportskey", JSON.stringify(sports)); // store as a string
document.getElementById('output').innerHTML = window.localStorage.getItem('sportskey');
}
答案 1 :(得分:1)
问题在于变量的范围。您的sports数组必须在myFunction()函数之外声明
<script>
var sports = ["soccer", "baseball"];
function myFunction() {
var newSport = document.getElementById('textInput').value;
sports.push(newSport );
var myString= JSON.stringify(sports);
window.localStorage.setItem("sportskey", myString);
document.getElementById('output').innerHTML = window.localStorage.getItem('sportskey');
}
</script>
答案 2 :(得分:0)
每次调用sports
时,您都在重新创建 myFunction()
数组。每次添加新元素时,都是从头开始,添加第3个元素,忽略已添加的其他元素。
仅在localStorage
中不存在的数组中创建数组。
P.S。您不能将数组存储在本地存储中,只能存储字符串。您需要转换为/从JSON转换才能使其正常工作。
function myFunction() {
var sports = JSON.parse(window.localStorage.getItem('sportskey')) || ["soccer", "baseball"];
var newSport = document.getElementById('textInput').value;
sports.push(newSport)
var json = JSON.stringify(sports);
window.localStorage.setItem("sportskey", json);
document.getElementById('output').innerHTML = json;
}
答案 3 :(得分:0)
Aaargh ......我的回答太迟了;)
是的,每次调用方法时都要重新创建数组,并且在从localStore加载项时,应该在存储项和JSON.parse(string_from_localStore)时调用JSON.stringify(Array)。
但是你应该将stringify包装在try和catch块中,因为当json字符串格式不正确,你的stringify方法崩溃了函数并且它停止工作时,这可能是一些原因。
var myFunc = function() {
//load it at first from localstorage
var sports = ["soccer", "baseball"];
var localSports = [];
try {
localSports = JSON.parse(window.localStorage.getItem('sportskey'));
if( localSports == null)
localSports = sports;
} catch(ex) {
console.log("something wrong");
localSports = sports; //fallback
}
var newSport = document.getElementById('textInput').value;
localSports.push(newSport); //this is an array
//insert the array with JSON.stringify so you can take it later out and rework with it
window.localStorage.setItem("sportskey", JSON.stringify(localSports));
output.innerHTML = window.localStorage.getItem('sportskey');
};
以下是jsfiddle的链接: